teem	/	unrrdu	unu slice

unu slice: Slice at a position along an axis. Output nrrd dimension is one
less than input nrrd dimension. Per-axis information is preserved.

Usage: unu slice -a <axis> -p <pos> [-i <nin>] [-o <nout>]

-a <axis> = axis to slice along (int)
 -p <pos> = position to slice at:
          o <int> gives 0-based index
          o M-<int> give index relative to the last sample on the axis (M
            == #samples-1).
 -i <nin> = input nrrd
-o <nout> = output nrrd (string); default: "-"